The present invention relates to aircraft air management systems. In particular, the invention relates to bleed air systems for supplying compressed air to an aircraft air management system.
Aircraft air management systems supply bleed air to a variety of aircraft systems, such as an environmental control system to maintain aircraft cabin air pressures and temperatures within a target range for the safety and comfort of aircraft passengers, anti-icing systems, air-driven pumps, etc. This is done through the use of compressed air taken from two compressor stages (bleed air) of at least one of the bypass turbine engines propelling the aircraft. Each of the two air pressures available from the compressor (intermediate pressure (IP) and high pressure (HP)) are directed to the air management system through pressure lines or plenums. A pneumatic valve controller operates a series of pneumatically operated bleed valves in response to electronic control signals from the air management system to control the relative flows of IP and HP compressed air flowing to the air management system. Air pressure in the pressure lines is measured by at least one pressure sensor which provides this information to air management system. The air management system uses the air pressure information along with other information from around the aircraft to direct the pneumatic valve controller to provide the desired bleed air flow to the air management system.
The bleed valves, pressure sensor, and pneumatic valve controller are exposed to extreme conditions. These components operate near the compressor of the bypass turbine engine, in an environment of extreme vibration. In addition, the compressed air is extremely hot, in excess of 600 degrees Fahrenheit. This extreme heat and vibration are major factors leading to failure of these components.